My initial impression:
Warrior DK seems good/great for tempo warrior. Tempo warrior might make a big return. Works great with Gromm and Rotface, though Rotface, Gromm & DK might be too top-heavy for tempo list, I could see Rotface not making the cut.
Warlock DK has great effects (battlecry & hero power). No discard synergy means Warlock are struggling to find a deck. Maybe this DK gives them the sustain to bring back a control list or demon list. Tough to see where they go atm. The hero power is so insanely strong though, it can even be used as a 3 damage nuke to opponent's face. Possibly a Kazakus list will work now that they have an end game heal machine.
Warlock straight up power-creeped Drain Life, new spell is 2 mana, does same thing EXCEPT it can actually heal you MORE if there is spellpower in play... so 3 mana drain life strictly worse than 2 mana drain soul. (Drain life can target hero, drain soul is minion only).
Lich King is REALLY tough to gauge... 2 of the spells I don't want in my hand, the others are OP as hell. It's an RNG clown fiesta. Death Grip literally STEALS a card from your opponent's deck. Frostmourne is OP, but at 1/8 chance, how seriously do you save weapon removal for it? Anti-Magic Shell is crazy OP. I don't really ever want to play Army of the Dead or Doom Pact as a control player, but mid-range decks will, but will mid range decks play Lich King?
Stonehill Defender can discover Lich King. Paladin OP OP.